1. Technical Field
The present technology relates to a pneumatic tire and particularly relates to a pneumatic tire unit by which air flow around a tire can be improved.
2. Related Art
Japanese Unexamined Patent Application Publication No. 2010-260376A describes a conventional pneumatic tire including both a plurality of concave portions (recesses) and a plurality of convex portions (protrusions) throughout a tire circumferential direction and a tire radial direction in a predetermined region of a tire outer side surface for the purposes of effectively reducing air resistance around the tire and improving the fuel economy of a vehicle on which the tire is mounted.
Additionally, Japanese Unexamined Patent Application Publication No. 2010-30547A describes a conventional pneumatic tire including a plurality of concave portions (dimples) and convex portions (pimples) as agitators on a tire outer side surface (outer surface of side portions) for the purpose of preventing reduction in durability caused by heat buildup.
With the pneumatic tires described in Japanese Unexamined Patent Application Publication No. 2010-260376A and Japanese Unexamined Patent Application Publication No. 2010-30547A, it is recited that turbulent flow (agitation of air) around the tire is generated by the concave portions when the vehicle is traveling, and an increase in the effects of generating turbulent air (agitation effects) is sought by the convex portions. That is, the concave portions are described as portions that cause turbulent flow or agitate the air, and the convex portions are described as portions that promote the turbulent flow or agitation of the air.
However, in cases when a vehicle on which pneumatic tires are mounted travels, the air separating from the pneumatic tire on a leading side of the vehicle tends to expand toward the outer side of the vehicle; and the air separating from the pneumatic tire on a trailing side of the vehicle is prone to collect due to the influence of a wheel housing or vehicle components and tends to expand toward the outer side of the vehicle. Therefore, a negative pressure region on a back surface side of the vehicle enlarges, which becomes air resistance.